This invention relates to the field of weight measurement devices. More particularly, this invention relates to a weighing apparatus for those heavy loads necessitating lateral support during weighing, particularly where available space on either side of the load is relatively restricted.
While the present invention is generally suitable for the above stated purpose, it is particularly well suited for the weighing of casting ladles used in revolving turrets during continuous casting, and will therefore be described in connection with that particular field of application.
Revolving ladle turrets, as described in U.S. patent application Ser. No. 439,354, now U.S. Pat. No. 4,436,293, which is assigned to the assignee hereof and incorporated herein by reference, provide a means of quasi continuous casting. In Pat. No. 4,436,293, one of the two casting ladles used in the turret occupies the operating, i.e., casting position, while the other ladle occupies the stand-by position. As explained in detail in the patent, at any given time, it is important to know the liquid level in the operating ladle, so as to accurately determine the point at which the ladle has been emptied. As a result, ladles are typically suspended in vertically movable frames or similar supports, which in turn rest on pressure cells.
Although suitable for its intended purposes, one problem present in the above apparatus for determining the weight of a ladle, is that the directional force of the weight of the ladle usually does not coincide with the vertical axis of the pressure cell (due to the non-uniform distribution of the mass and contents of the ladle). As a result, horizontal force components develop between the guides of the frame and the overhanging suspension arms of the revolving turret which act to falsify the overall results of the weighing operation.
In the above described U.S. Pat. No. 4,436,293, these horizontal forces are compensated, for example, by horizontal laminations provided between the vertically movable frames and the overhanging arms of the turrets. It has been found that this lamination system reduces the weighing error to between about 1% to about 0.1%. Although this degree of accuracy may be regarded as highly satisfactory, particularly in view of the rough conditions under which this weighing process is carried out, there is nevertheless a need for still greater weighing accuracy.